Instant runoff in Burlington: 99.99% valid ballots in mayoral race

[March 12 update: Burlington did a partial recount of the mayoral race that confirmed the results. Note that three of the four ballots thought to be invalid were part of the recount -- and turned out to be valid. That means only one official invalid ballot was cast. And that quite possibly should have been valid too....]

Some incredible numbers coming out of Burlington, Vermont and its instant runoff voting election for mayor this week should once and for all dispel any concern that ranking candidates is hard for voters.

Out of close to 9,000 ballots cast in a mayoral race with five candidates, there was only a single undervote -- e.g.,. no first choice. Only four ballots had an overvote, and those four were where someone voted for a candidate and ticked off the write-in box too. Four invalid ballots out of nearly 9,000 ballots is amazingly low for any election. It means that more than 99.95% of ballots were valid, as compared to less than 99.0% of ballots in our American presidential races.
The City didn't do anything special on voter education either. What it did do was develop a good ballot design with clear ballot instructions. The voters took it from there. See data and round-by-round results at Burlington Votes.